ENTRAPMENTSITE 1
•A common cause of radial nerve entrapment in this area
is humerus fracture. The estimated incidence is 10–18%
(Bodner et al, 2001). Most are neurapraxic, with return
of function by 4–5 months (Kimura, 2001). Saturday
night/honeymooner’s palsy,the most common nontrau-
matic radial nerve lesion in the upper arm is also due to
compression near the spiral groove. Deep sleep (mostly
after excessive alcohol consumption) prevents aware-
ness of discomfort and repositioning.
- Symptoms and signs:Frequently there is deformity
of the humerus. Neurologic lesion presents with a
wrist drop, slight weakness of elbow flexion caused
by involvement of the brachioradialis. The triceps
may be involved, but frequently is not. The triceps
reflex may or may not be absent. There may be pain
or numbness in the posterior antebrachial cutaneous
and mostly in the superficial radial nerve distribution. - Treatment:Bony stability is the first requirement in
preventing further radial nerve injury after humerus
fracture. Most radial nerve lesions are neurapraxic.
Treatment can be conservative management, if nerve
continuity can be demonstrated with stimulation
study. If spontaneous recovery does not occur in sev-
eral months surgical exploration is indicated.
ENTRAPMENTSITES 2 AND 3
- Anatomy: At the elbow the radial nerve passes
through the radial tunnel (entrapment site 2), which is
formed by the lateral intermuscular septum, the
brachialis and brachioradialis muscles, until it reaches
the supinator (the end of the radial tunnel). Radial
tunnel syndromeis controversial. It usually refers to a
treatment resistant chronic tennis-elbow. There is no
definite neurologic deficit that can be demonstrated
clinically or by electrodiagnosis. - Posterior interosseous nerve:Syndrome is a com-
pression at the Arcade of Frohse where the radial
nerve pierces the supinator and becomes the posterior
interosseous nerve (PIN), which is purely motor.
Risksare mainly repetitive motion, scarring, lipomas,
or other space occupying lesions. Imaging may help
to demonstrate the cause. Surgery is frequently
needed to free the nerve. - Symptoms and signs:Partial wrist drop with radially
deviated wrist extension present. No sensory deficits.
Interossei appear weak secondary to loss of wrist sta-
bilization. - Treatment:Conservative management. If no improve-
ment, consider surgical release.
ENTRAPMENTSITE4—HANDCUFFNEUROPATHY
- Handcuff neuropathyoccurs at the wrist and is mostly
a purely sensory lesion, where the superficial radial
nerve is compressed against the radius. At riskare
prisoners—most common neurologic complaint of
US prisoners returning from Operation Desert Storm
(Cook, 1993). With more severe injury multiple
nerves may be involved. Recovery is mostly complete
within 6–8 weeks. Symptoms include sensory deficits
in superficial sensory nerve distribution. Treatment is
through conservative management.MEDIAN NERVE- The median nerve is one of the three nerves supplying
all muscles of the forearm and hand. - Anatomy and origin: C6–T1 nerve roots/spinal
nerves. It traverses the upper, middle, and lower trunk,
the anterior divisions, and the lateral and medial cord.
It has five sites of potential entrapment.
ENTRAPMENTSITE1—LIGAMENT OFSTRUTHERS- Anatomy:Some subjects have an anomalous supra-
condylar process on the humerus, from which a
fibrous band arises and attaches to its medial epi-
condyle. This structure can entrap the median and/or
the ulnar nerves and the brachial artery. - Risk factor:At risk are the 2.7% of the population
who have the anomaly. - Symptoms and signs:Tingling, numbness, and weak-
ness in all median innervated muscles. Sometimes the
ulnar nerve may also be entrapped. Imaging studies
may demonstrate the presence of the anomaly. - Treatment:The reduction of aggravating activities
and anti-inflammatory medications may help some,
but surgery will usually be the treatment of choice.
ENTRAPMENTSITE2—PRONATORSYNDROME- Anatomy:In the antecubital area the median nerve
is located underneath the bicipital aponeurosis (lac-
ertus fibrosus). Then it passes between the superfi-
cial and deep heads of the pronator teres, located
underneath the flexor digitorum superficialis.
Entrapment by these structures is known as pronator
syndrome. An accessory head of the flexor pollicis
longus(FPL) called Gantzer’s muscle may also con-
tribute to the pronator as well as the anterior
interosseous nerve syndrome (site 3). An anomalous
isolated brachialis muscle tendon may cause com-
pression. - At risk:At risk are pianists, fiddlers, harpists, base-
ball players, machine milkers, dentists. - Symptoms and signs:Pain on active resistive forearm
pronation. There may be cramping of fingers or writer’s
cramp. Provocative maneuvers include paresthesias in
the hand after 30 s or less of manual compression of the
326 SECTION 4 • MUSCULOSKELETAL PROBLEMS IN THE ATHLETE